*{
    margin: 0;
    padding: 0;
    border: 0;
}
html{
    font-size: 62.5%;/*  公式16px*62.5%=10px  */  
}

body{
    padding-left: 10px;
    padding-top: 10px;
}
.brand{
    font-size: 4rem;
    user-select: none;
    width: 20rem;
    height: auto;
    background-color: #66ccff;
    border: 1px solid black;
    box-sizing: border-box;
}